Aquatic macroinvertebrates as bioindicators of the harvest effect on mountain streams afforested with exotic pines

Abstract

Land use change is one of the main factors affecting stream ecosystems since it modifies aquatic-terrestrial linkages and then structure and functioning as well. The aim of this study was to evaluate the effect of harvest on mountain afforested streams (Córdoba, Argentina). We explored the macroinvertebrate community changes after harvest and applied biotic and multimetric indices using natural grassland streams as a reference condition. Physicochemical variables were measured and benthic invertebrate samples were collected in three streams draining grasslands (reference streams) and three contiguous streams draining plantations of Pinus elliottii over four years (2008, 2012, 2014 and 2015). Some afforested streams were harvested in 2012 and the others onwards. Assemblages did not differ between grassland and afforested stream, according to the results of the multivariate analysis. Richness and diversity were higher in grassland streams than in the afforested ones, without distinction among pre and post-harvest conditions. The multimetric indices and BMWP index, confirmed some degree of deterioration in afforested and harvested streams. Our findings may constitute a valuable tool for the development of management strategies that attempt to preserve the ecological integrity of stream systems in forestry environments.